December
4, 2001
The Honorable
Christine Todd Whitman
Administrator
U.S. Environmental Protection Agency
1200 Pennsylvania Avenue, NW
Room 3000
Washington, DC 20460
Dear Administrator
Whitman:
EPA is engaged in the critical task of reducing the public health
risks associated with exposure to air pollution. In recent months,
we have discussed with your staff the health risks (e.g., hospital
admissions and premature deaths) associated with fine particulate
matter (PM). We share your commitment to develop legislative and
administrative programs to reduce public exposure to PM. The purpose
of this letter is to highlight some critical research needs that
can help target environmental-protection investments to the most
important sources of PM and thereby better inform cost-benefit studies
of future air pollution control policies.
We understand that EPA is now devoting a substantial share of its
research budget to better understand the effects of PM on public
health. We support this research effort and recommend that it focus
on the following critical issues: (1) potential confounding of PM
health effects with other pollutants in the air; (2) attribution
of the PM health effects to specific constituents (e.g., sulfates
versus nitrates versus organic and elemental carbon, and metals),
and (3) the quantitative relationship between exposure to different
particles and various health effects. The National Academy of Sciences
(NAS) Committee on Research Priorities for Airborne Particulate
Matter, chaired by Dr. Jonathan Samet, identified a similar set
of issues in its 1998 Report and continues to advise EPA on its
research program. We are also encouraged that the NAS Committee
on Estimating the Health-Risk Reduction Benefits of Proposed Air
Pollution Regulations, chaired by Dr. John Bailar, will be identifying
important research needs in this area. We also support the university-based
centers on PM research that have been established to address these
central issues.
Based on our reviews of EPA's recent rulemakings on air pollution
and the agency's 2001 Regulatory Plan, it is clear that we need
to understand better which sources of PM in our economy are responsible
for the PM-related health effects. At the present time, there is
no scientific consensus about what toxicity values are appropriate
for specific types of particles and, as a result, EPA has adopted
a default position in past regulatory analyses that all particles
are equally toxic. However, there is emerging evidence that some
types of fine particles may pose a greater health risk. The more
recent multi-city studies suggest that PM appears to be more harmful
in some cities than others, variation that may be attributable to
the different kinds of particles found in different cities. Studies
vary in their findings about which sources of PM are most strongly
related to mortality, identifying a variety of sources from coal
combustion and oil burning to the emissions from motor vehicles.
The Electric Power Research Institute (EPRI) is undertaking in Atlanta
a new study to address the questions raised by these studies about
whether all particles should be treated as equally toxic. The Atlanta
study is using more intensive monitoring data to explore the relationship
between specific types of fine particles and adverse health effects.
We believe that this question should be tested across a number of
different cities to determine whether there is a consistent pattern
in the relative toxicity of different particle types. The data collected
from EPA's "super-site" particulate monitors and from its speciation
network may play an important role in such research, however, it
may also be necessary to undertake additional monitoring to support
daily time-series studies of health effects. In order to facilitate
this research, we recommend that EPA consider a private-public partnership
program to perform this critical function. We recommend that any
such program provide at the outset for public release of collected
data for scrutiny and reanalysis, after the original investigators
have had the opportunity to publish their findings.
While we recognize that EPA has a research plan for PM, the plan
should be flexible enough to retarget some of EPA's $69 million
PM research budget to follow-up on critical questions raised by
research funded earlier in the program. If research can identify
those particles most responsible for health risks, it may be possible
to design controls that do more for public health and cost the economy
less than would occur through policies that assume all particles
are equally toxic. Given the tens of billions of dollars of social
costs that will be devoted to PM emissions over the next 20 years,
this follow-up research should begin without delay in FY 2002.
As always, my staff and I look forward to working with you on this
important issue.
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Sincerely,
/s/
John D. Graham
Administrator
Office of Information and Regulatory Affairs |
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